Drying and ventilating method and apparatus for material-drying plants



June 15 192 6. 1,588,834

E. L. HOGAN ET 1.

DRYING AND VENTILATING METHOD AND APPARATUS FOR MATERIAL DRYING PLANTS Filed May 8. 1924 10 sheets sheet 1 vwewto ps. WzQ/p ZWw/ M Q 6 'itowigq:

10 Sheets-Sheet 2 Suva view y Y flit Tuneup.

E. L. HOGAN ET AL Filed May a, 1924 June 15 1926.

DRYING AND VENTILATING METHOD AND APPARATUS FOR MATERIAL DRYING PLANTS- June 15 ,1926. 1,588,834

E. L. HOGAN ET AL DRYING AND VENTILATING METHOD AND APPARATUS FOR MATERIAL DRYING PLANTS Filed May 8, 1924 10 Sheets-Thea 5 fi/W E 1 5mm? June 15 1926.

E. L. HOGAN ET AL.

DRYING AND VENTILATING METHOD AND APIPARATUS FOR MATERIAL DRYING PLANTS WI'M aflomws' 10 Sheets-Sheet 4 amvemtozs.

Filed May 8' 1924 whK Jun 1s 1926. 1,588,834

E. L. HOGAN EI'YAL DRYING AND VENTILATING METHOD AND APPARATUS FOR MATERIAL DRYING PLANTS File y's, 1924 10 Sheets-Sheet 5 N X olellulelololenqli A June 15 1926".v

1,588,834' E. L. HOGAN ET AL DRYINQ AND VENTILKATING METHOD AND APPARATUS FOR MATERIAL DRYING PLANTS Filed May a. 1924 10 Sheets-Sheet 6 aM W June 15 1926. 1,588,834

E. L. HOGAN ET AL DRYING AND VENTILATING METHOD AND APPARATUS FOR MATERIAL DRYING PLANTS Filed May a; 1924 10 Sheets-Sheet v I mozutozs: W/MW' wmaz mzfl t M 8 8 8 I aw W9;-

June 15 1926. 1,588,834

E. L. HOGAN ET AL DRYING AND VENTI LATING METHOD AND APPARATUS FOR MATERIAL DRYING PLANTS Filed May 8, 1924 10 Shee ts-Sheet s Svwmto w/zmw June 15 1926.

E. L. HOGAN ETAL DRYING AND VENTILATING METHOD AND APPARATUS FOR MATER'IALDRYING PLANTS Filed May 8. 1924 10 Sheets-Sheet 9 s w M z w m 8 m m no u a "m m 8 u I M June 15 1926. 1,588,834

E. L. HOGAN ET AL DRYING AND VENTILATING METHOD AND APPARATUS FOR MATERIAL DRYING PLANTS Filed-May 1924 10 Sheets-Sheet 10 Patented June 15, 1926.

UNITED STA TES 1,588,834 PATENT OFFICE;

EDWARD L. HOGAN, OI DETROIT, MICHIGAN, AND GEORGE S. WITHAM, JR., OI HUD- SON FALLS, NEW YORK, ASSIGNORB TO AMERICAN BLOWER' COMPANY, OF DE- TROIT, MICHIGAN ,A CORPORATION 01 NEW YORK. 7'

DRYING AND vnnrnza'rme mnrnon Ann arram'rus roa MATERIAL-DRYING rnmrs. Y

Application filed m a; 1924. Serial 10,711,859.

This invention relates to an im roved "dry;

ing and ventilating method an apparatus for material drying plants, particularly paper drying and analogous plants. I

In paper drying plants and other manufact'uring plants employing various kinds of drying apparatus and open treating vats,

large volumes of 'hot' vapor and steam are I given off from the drying machine, vats, or the like, filling the machine room with heavy moisture laden air, a condition hi hly objectionable to operatives and harmflfi to the building and equipment. Also, in the case of paper driers and the like, the hot moist air pervading the machine room materially slows up the drying process and results in uneven dryingof the web due to I condensation thereupon and reabsorption of moisture thereby.

As will be readily appreciatedwhen the exhaust hot air andvapor are. permitted to escape outside the drying plant to the atmosphere, the waste heat is enormous, especially so in the operation of paper drying plants in which it is common practice to supply heated air to the machine to assist in the drying operation.

It has heretofore been-proposed to remedy these conditions by circulating such a large volume of heated air throughout the whole machine room'as' to maintain a relatively dry condition of the air ,in the machine room after the same mixes with the vapors given off from the drier but the expense of fuel necessary to supply the lar e amount of heated air required during cold weather renders such a system wholly impracticable. Another suggested method .is to suppl heated air in a plurality of blasts laterally of the rolls at localized points at the vapor pockets between the rolls, and to use a hood isposed over the upper side of the rolls to collect the exhaust vapor but while it is advantageous to provide currents of-heated air laterally of the-rolls in efi'ecting the dissipation of the vapor from the pockets between the rolls and in assisting in the drying operation, this method is manifestly unsatisfactory for with the air blasts delivering arran ed over the rolls and will escape from the si e of the rolls into the machine morn,

Methods have also been devised for the purpose of recovering heat from the exhaust vapors, but by these prior systems only a relat vely small proportion of the heat of the exhaust vapors is. reclaimed.

The object of the present invention is to overcome the difliculties hereinbefore referred to; to prevent the escape of the exhaust vapors into the machine room with the consequent injury to the building structure and equlpment, and the attendant unsatisfactory atmospheric conditions for workmen; to prevent condensation upon and re-absor tion of moisture by thematerial'; .to provi e fora inoreexpeditious, uniform and efiicient drying of the material, and also to recover and utilize a large proportion of the heat of the exhaust vapors, whereby a considerable savin in the operatingexpense of such plants wi 1 be effected, the output increased, and a superior product obtained. I

In accordance with our improved method, a flow of heated air is provided transversely of the paper drying machine or the like,

provision is made for preventing escape of vapor from the top of the machine into the .machine room while providing against condensation of vapor at the upper side .of the rolls, and the exhaust hot air and vapor istrapped and conducted ofi from the other side of the machine. and vapor is passed through a chamber, and water in a finel divided condition is cir-.

The exhaust hot air culated within t e chamber in the ath or the exhaust hot air and vapor to effect a thorough transference of the heat of the exhaust vapors to the water, and the drying and conditioning of the air for reuse; The heated water is utilized for various manufacturing operations about the v heating or other purposes, and-t e dried air after the treatment within the chamber, is

re-heated, and returned to'the drying machine for use over again for drying purposes. The invention contemplates maintaining a lateral flow of a. relatively high volume of heated air completely about the heated rolls lant or for and throughout the web, as distinguished from suppl ing heated air in a multiplicity of jets or blasts at localized points at the vapor ockets, and the exhaust hot air and vapor is prevented from esca ing into the machine room, all of the aust hot air and vapor being trapped, conveyed off and treated to reclaim the heat therefrom and to recondition the air for use over again, the atmosphere of the machine room being kept entirely free from the exhaust vapors. Any conventional from of heating means is employed for maintaining the desired room temperature in the machine room. The heated air supplied to the drying machine is of a higher temperature than that required for the airof the machine room, and the invention contemplates mixing some of the air from the machine room with air of a higher temperature and supplying the resultant mixture to the drying machine, and also introducing some of the reconditioned air from the system into the machine room for heating purposes, these features of the system further carrying out the purpose of reclaiming and utilizing a large proportion of the heat of the exhaust hot air and vapors, and economy in the operation of the plant.

The invention, with other objects and advantages thereof, will be understood from the hereinafter contained detail description, when considered in connection with the accompanying drawings forming part hereof and illustrating one embodiment of an apparatus for practicing the method.

In the drawings:

Figure 1 is an end elevation of an apparatus constructed in accordance with the present invention.

Fig. 2 is a top plan view.

Fig. 3 is a front elevation.

Fig. 4 is a detail section on the line H Figure 1.

Fig. 5 is a detail horizontal section on an enlarged scale of the heat recovery and air conditioning device.

Fig. 6 is a detail vertical section on an enlarged scale of the heat recovery and air conditioning device.

Fig. 7 is a detail transversesection, on an enlarged scale, of the hood.

Fig. 8 is a detail View, on an enlarged scale, of the emergency outlet, the damper means, and the automatic damper operating means or control.

Fig. 9 is a detail plan view of the controller.

Fig. 10 is a detail side view of the controller.

Fig. 11 is a detail section of the controller on the line 11-11 of Figure 12.

Fig. 12 isa detail section of the controller on the line 12-1-2 of Figure 10.

Fig. 13 isa detail view, part section and part side elevation, of a' modified form of the'controller.

Fig. 14 is a detail view, on an enlarge scale, of manual operating means for the damper means.

Fi 15 is an end elevation of a slightly modified form of apparatus. I

i one side of the machine.

Fig. 16 is a top plan view of the modified form of apparatus illustrated Figure 15.

For carrying out the improved method, the invention comprehends an apparatus including a hood arranged to extend over the top) of the series of heating rolls, and an ex aust apron at one side of the machine for trapping and carrying off the exhaust hot air and vapor. More particularly the invention contemplates a hood having an interior chamber in the wall thereof extending completely throughout the same, with an air intake to said chamber and a discharge outlet from the chamber disposed at one side of the machine, and the supplying of heated air to the interior of the chamber in the wall of the hood, said hood'being adapted to serve as means for preventing escape of vapor from the top of the machine;

asinsulating means against the lower temperature air of the machine room, and also as a distributor for heated air to the machine.

In the drawings, the invention is shown applied to a conventional form of paper drying machine of the heated roll type. 1 designates the floor of the machine room 2 of a paper drying plant, 3 the basement or room below, 4 the series of steam heated rolls of the paper making machine, 5 the pit beneath the series of rolls, and 6 the paper web.

Referring to a detail description of the particular apparatus illustrated Figs. 1 to 12 of the drawings, 7 designates the hood arranged over the top of the paper making machine, and 8 the exhaust apron located at The exhaust apron 8 is vertically disposed, extending throughout the length andheight of the series of rolls 4, and preferably, as shown, the same extends from the floor 1 to a point above the horizontal plane of the top of the series of rolls 4. The particular construction of apron shown, comprises a main wall 8 with marginal side and end walls 8, 8, and an outlet 8; the entrance side of the apron facing the side of the series of rolls 4.

-The hood 7 extends throughout the full length of the series of rolls 4 and to either Side thereof, said hood preferably extend ing from a point immediately adjoining the upper end of the apron 8 at the rear side of the machine to the front side thereof. in the particular exempliiication illustrated in the drawings, the same being shown extending at a downward inclination to the front side of the machine. At its front side the hood 7 is provided with :1 depending portion 7 extending to the front side of the machine, said depending portionterminating short-of the floor 1 leaving an open space at this point below the lower front marginal portion of the hood for the entrance of air to the machine from. the machine room. The hood 7 has double walls 7", 7, spaced as shown, providing an interior chamber (1 throughout the same. The interior chamber a is closed at the ends of the hood-by end walls 7 7, extending .between and con; nected with the walls 7", 7 At its rear side,

the hood has an air'intake opening 7 leadin to its interior chamber a, said 1nta e opening extending throughout the full length of the hood, and 9' is a distributing I length of the hood to deliver air throughout.-

or feed duct extending along the rear side of-the hood 7 and having an outlet co -extensive with and communicating with the intake opening 7 of the hood 7. The hood 7 at its front side has an outlet from its interior chamber a extending throughout the the length of the series of rolls. For this purpose, in the construction shown, the spacebetween the upper and lower walls of the hood at its front lower marginal edge is left free, providing a longitudinally extend ing outlet '7 The hood 7, whichis suspended over the drying section of the paper making machine by hangers from the roof trusses or from columns (not shown) may be constructedof any suitable material, the construction shown being formed of metal,

I galvanized iron, aluminum, or the like.

The apron 8 is securedgin position by any suitable means for instance by brackets (not shown) connected with the floor 1 and framing of the paper making machine.

.The outlet 8 of the exhaust apron 8 is connected with the distributor or heated air feed duct .9 by a duct having an exhaust section 10 leading off from the apron 8, and

a return section 15. Interposed in said duct is' a combined heat recovery and air treating device 11, and also suitable air circulating means, for instance, a fan or blower 12, the combined heat recovery and air treating device 11 and the fan 12, being shown located in the basement 3, the exhaust duct section 10 having a rearwardly extending horizontal part 10 connected directly wit the inlet end of the combined heat recovery and air conditioning device 11, and the outlet end of the latter being directly connected with the suction side of the fan 12.

Means is provided for heatlng the air after its passage through the heat recovery and air conditioning device 11, and for this purpose the invention comprehends the use in the system, either separately or together, of 'a heat interchanger or device 13 for subjecting the air to indirect heating b the exhaust vapors, and also a closed *ortu ular heater 14, these heating means being shown associated with the return duct section 15 which leads fromthe outlet side of the fan 12 to the distributing or heated air feed duct 9 of the interior chamber a of the hood 7 Referring particularly to Figs. 5 and 6 of the drawings, theparticular form of heat recovery and air conditioning apparatus shown comprises, a chamber or conduit 18, the same being shown as rectan lar shape in crosssection with tapering mi; and out let portions,18, 18 andhorizontally disposed. The chamber 01 conduit 18 is provided with a plurality of spray deviceslocated at intervals along the same, and

means is provided for circulatin'g water through the spray devices in successive stages, progressively starting from the outlet end portion 18\ of the chamber or conduit. Any suitable formlo'f spray device may be employed, the particular construction showtn comprising a main pipe section 19 extending horizontally across the lower part of the chamber or conduit through one side wall thereof, and provided with-vertical vbranch pipes 20 having a multiplicity of relatively shortlateral extensions 21 which are provided with nozzles 22.

The water circulating means includes a,

system of pumps 23 and a series of troughs 24 located along'the bottom of the chamber or conduit 18 to receive the water from the spray devices,the spray. devices being shown arran ed in sets of two, a trough 24 being provided for each set of sprays. 25 designates a water sup-ply pipe having branches,

25, 25", leading to the first set of spray devices and 26, 27, are connections between the system of pumps 23 and the other sets of spray devices 19 and the. troughs 24 excepting the first one of the series. Each of the troughs 24 is provided'with a short overvflow pi e 24, that connects with a main drain pipe 24", leading to any suitable point providing for the carrying away of any excess water and also for washing out the heaters and troughs. One of the tanks is pro- W vided with-a fresh water inlet connection 28 whereby the tanks maybe filled, when the equipment is started. 29 designates equal-. izer connections betwe n the troughs 24, and 30 is a float valve in one of the troughs for maintaining a constant water level throughout the series of troughs.

In conjunction with the spray devices, a series of closed or tubular heaters 31 is provided, the same, in the particular form of apparatus shown, being located within the influence of the vapor stream in the inlet end portion 18 of the chamber or conduit 18. 32 is-a pump suitably connected for .cir-' cula'ting the water from the first of the iso nator plates at the rear side of each set of spray devices, and 35 are deflectors extending inwardly from the walls of the chamber 18 at a rearward inclination, said de tlectors acting to direct the vapor inward ly from the walls of the chamber and being arranged at intervals along the chamber, one of said deflectors being located directly in advance of each of the series of. baflle plates 34.

The heat interchanger 13 may be of any suitable construction, the particular construction shown, comprising metal pipe sec tions or casings 13, 13", of varying diameters arranged one within the other in spaced relation providing passages 13, 13, extending close together for the treated air and the exhaust vapor, the smaller casing 13 being interposed in the return supply duct section 15, and the larger casing 13 connected in the exhaust duct section so that the treated air from the heat recovery and conditioning device 11, passing through the inner chamber 13 of the heat interchanger is brought in intimate relation with and heated by the exhaust vapors flowing in the opposite direction through the outer chamber 13 of the interchanger. In the construction shown, the heating of the treated air by the exhaust vapor is further increased by arranging the supply and exhaust ducts 15, 10, close together, the sup ply duct having a vertical leg 15 and a horizontal extension 15 extending along side the vertical section 10 and the horizontal part 10 of the exhaust duct 10. The interchanger 13 is provided with a valve controlled intake 36 leading from the machine room into its outer exhaust vapor passage 13, and a valve controlled outlet 37 leading from the inner chamber 13 to the machine room, providing for the mixing of some of the air from the machine room with the exhaust vapors, and the introduction of some of the treated conditioned air from the system to the machine room. 38, 39 designates valves or dampers of conventional form for the intake and outlet 36, 37. The system may also be provided with avalve controlled passage 40 leading from the machine room into'the distributing duct 9 providing for introduction of some of the air-from the machine room into the system at this point. Any suitable type of closed or tubular heater 14 or series of such heaters may be employed. The tubular heater shown is one of the well known construe tions consisting of a series of coils in which is circulated hot Water or steam from any convenient source (not shown).

41 designates a branch pipe leading from the return duct section 15 for supplying conditioned air to the pit 5 for circulation at the under side of the series of heating rolls 4, said branch pipe connecting with a distributing pipe 42 extending within the pit 5 centrally and longitudinally of the series of rolls 4, and being provided with suitable outlet orifices along the same.

The hot air and vapor from the exhaust duct section 10 is circulated through the chamber or conduit 18 of the heat recovery and air conditioning device in the direction 01 the arrow. The water introduced through the supply pipe 25 and circulated in succession through the sets of spray devicesis discharged in fine sprays into the chamber in the path of the hot vapor stream at diti'erent points along the same in a direction counter to the flow of the exhaust vapors through the conduit, the water, being subjected to progressive stagesvof temperature treatment,'and the air to repeated water spray treatments, with the cooler water being brought in contact with the cooler air or vapor, the warmer water with the warmer air or vapor and ultimately the warm water being brought in contact with the relatl\'6ly warm air or Vapor. The breaking up of the water in fine sprays in the path of the exhaust vapor provides a large amount of surface contact of the water with the eX- haust air and vapors, a thorough transfcrenee of the heat of the hot vapors to the water being eiiected. During the passage of the. vapor through the conduit, the series of bafiie plates 34 serve to agitate and break up the exhaust vapor, assisting in the complete contact of the water throughout the entire body of vapor, the series of battles also functioning to separate or extract the water from the exhaust vapors after each water spray treatment, preventing the mixture of the water in the various units and inter- "fercnce with the progressive temperature stages of treatment. After the successive stages of water spray treatment, the temperature of the water is further increased by its passage through the series of closed heaters 31,1rom which the water is finally drawn off through the conduit 33 to a suitable storage tank, (not shown), or the same may be used immediately, as desired, for various purposes. The air after its passage through the treating chamber and being subjected to the successive water spray treatments, in a dried condition, passes to the heat interchanger 13 and the closed heater 14, is heated thereby, and then passes to the feed duct 9. From the feed duct 9, the heated reconditioned air circulates throughout the interior chamber a in the wall ofthe hood 7, passing across the same and out of said chamber through the outlet 7 to the front side of the machine, the air being distributed all along the series of rolls. The heated air issuing from-the outlet 7 is directed laterally and inwardly toward the rolls and flows transversely of the machine and web 6 due to the forcing failure of the pumps'of the system to oper- 6 through the branch pipe 41 and distributing pipe 42, so that a lateral flow of a large volume of conditioned air is maintained about the heating rolls and web. 'Under this condition of cross flow of conditioned air from one side of the machine, and with the hood arranged over the top of the machine, none of the exhaust vapor escapes into the machine room, the exhaust vapor being all trapped and drawn off through the exhaust apron 8 from one side of the machine. The hood 7, heated by the circulationof the heated air through its interior chamber a, while serving to prevent theescape of vapor into the machine room from the top ,of the machine also functions as a distributor for heated air to the. machine, and as insulating and heat transference means, acting to prevent condensation' of the vapor abovethe' rolls and web.

During the operation of the apparatus, air

from the machine .room may be introduced into the system through the valve controlled intakes 36 and to assist in the conditioning and tempering of the air, and heated airfrom the system may be introduced through the valved outlet 37 into the machine room for heating the air therein. a

' Provision is made in the system whereby should the air drying or dehumidifying.

means fail to function properly due-to failure or falling off of the water supply, or

ate properly on account'of motor or valve troiible, or the like, the exhaust hot air and vapors will not-be allowed to pass back through the return duct to the drying ma chine but will be carried ofi to theoutside atmosphere or other suitable place of exhaust. For this purpo'se'the duet connecting the outlet 8 of the exhaust apron 8 with the feed pipe 9 is provided with an emergency outlet, shown, in the present instance, as a branch 'pipe'50 leading from the lower part of the return duct section 15 through theiwall of the drying house to the atmosphere. Damper means and automatically acting operating means therefor are provided for controlling the emergency outlet and for closing the passage through the return duct section :15. The damper means may be of any suitable form, the

particular construction shown comprising dampers 51, 52, consisting of a plurality of vanes 51", 52 pivotally mountedand rovided with short cranks'51",'52","to,w ch '1 are connected operating rods 51, 52. Varions-types'ot automatic controls'or operating mechanism for the damper means may be employed. In Figures 8 to 12 of the drawings is illustrated, on an enlarged scale,

one form of automatic mechanism of the" well known fluid pressure actuated thermostatically controlled type-having. two ex-- pansible elements, one affected by the actual dry bulb temperature of the surrounding air, and the other aflected by the lower wet bulb temperature of the air produced by evaporating moisture around this element, the relative expansion orcontraction of the two elements being dependent upon the rela-' 'tion existing between the temperature and humidity of the airafl'ecting them. The particular automatic control or damper operating mechanism shown comprises a base 53v upon which a capsular spring 54 of con- I ventional type is mounted and connectedby means of a capillary tube 55 with a sensitive member in' the form of a bulb 56. A

main lever 57 is fulcrumed at '58 upon uprights 59 on the base 53 and isprovided with an adjustable projection in the form of a screw 60 which is maintained in contact with the capsular spring 54 by means =ofa "spring 61 located between and engaging one end of the lever 57 and the base '53. The

main lever 57 carries a capsular spring 62 j;

Y connected through the medium of adcapillary tube 63 with asensitive member in the form of a bulb 64. A secondary lever 65 is pivoted at 66 upon uprights 67 extending from the main lever 57, said lever 65 being. ro- I vi'ded' with an adjusting screw 68 w 'ch 1 bears against the capsular spring 62 and is maintained in contact therewith bv a spring 69 located between thetwo levers 57 and 65. The screw 68 carries a pointer 70 which cooperates 'with a suitable scale 71 provided upon'the lever 65 to visibly indicate the adjustment to which the adjusting screw 68 is set.

which is provided with channels 73 and 74 connected by means of pipes 75 and 76 with a source of air or other fluid under pressure (not shown) and with a diaphragm motor 77 constructed and arranged so that its rod 77' is moved. downwardly when premure is applied to the diaphragm, and moved upwardly- Mounted on the base 53 is a block 72 i under the action of a. spring 77' when the pressure upon the diaphragm is reheved. A

Attached to the block 72 is a-valve casing 78, said casing beingprovided with an inlet passage 7 9' communicating withthe channel 7 3 and thus with the supply of fluid under pressure, and said'chamiel has an outlet passage SOcommunicating with the channel 74 and the diaphragm motor 77; Both pas sages 79'and 80 are also -11]. connection with .ment by a chamber 81 in whicha valve 82 of the ball type is located, the passage 79 being formed with a seat for the accommodation of the ball valve 82. The ball valve 82 is arranged to also control 'an exhaust passage 83 which establishes communication between the chamber 81 and the atmosphere; a stem 84 extends through and beyond the exhaust passage 83 and at its inner end engages the ball valve 82 while its outer end is adapted for engagea lug 85 on the secondary lever 65. The diameter of the stem 84 is such that a space exists between it and the passage 83, the space constituting the actual exhaust passage previously mentioned. The capillary tube and bulb 56, and the tube -63 and bulb 64 are, in accordance with the common practice partly or wholly filled with a volatile fluid which will cause the-capsular springs 54 and 62 to expand when the bulbs are subjected to an increase in temperature and to contract when the bulbs are subjected to a decrease in temperature. The wet bulb 64 is provided with a wick 86 depending into a water tank 87 to which water is supplied through a suitable pipe 88 and in which an overflpw 89 is located-to conduct any surplus supply of water from thetank.

The dry bulb 56 and the wet bulb 64 are both located in the system, preferably, as shown, to the outlet side of the heat recovery and air treating device 11, see Figure 5 at the drawings. The rod '77 of the dia-.

phragm 77 is pivotally connected at its lower end with a lever 90. The lever 90 is pivotally connected at one end to a support 91 and at its other end is pivotally connected directly with the operating rod 51 of the damper 51 and is connected with one end of the operating rod 52 of the damper 52 by a cable 92, said cable passing over a pulley 93, the other end of the operating rod 52 of the damper 52 being connected with a cable 94 extending over a. pulley 95 having a weight 96 secured to its other end, the arrangement being such that normally, when no air pressure is applied t the diaphragm of the diaphragm motor 77 and the lever 90 occupies the position indicated in full lines in Figure 8, the damper 51 will be 'closed and the damper 52 opened, and when said lever 90 is moved downwardly by the diaphragm motor 77 to the dotted line position Figure 8, the damper 51 will be opened and the damper 52 closed. When the pressure is relieved upon the diaphragm of the diaphragm motor 77 the spring 77 actuates the diaphragm to move and hold the lever 90 in the full line position. In theupward movement of the lever 90the weight 96 serves to actuate the operating rod 52 of the damper 52 to open said damper.

The controller is adJuSted for a certain dry andwet bulb temperature throu h the adjusting screw 68 and its pointer O cooperating with the scale 71, so that under normal operating conditions of the combined heat recovery and air treating means 11 the emergency outlet 50 will be maintained closed and the passage through the return duct will be opened, but should the combined heat recovery. and air treating device 11, fail to function properly, so that the air passing therefrom contains a large percentage of moisture this will raise the .wet bulb temperature creating a higher pressure in the capsular spring 62 and thereby expand the same. This expansion is communicated to the screw 68 and pivotally moves the secondary lever 65 to compress the spring (59 and to lift the lug away from the end of the stem 84. It will be understood that the action of the capsular spring 62 and the movement of the secondary lever 65 are relative to the main lever 57. As the lug 85 is raised and thus relieves the stem 84 from restraint, the air pressure will cause the ball valve 82 to close the exhaust passage 83 and to establish communication between the channels 7980 by .way of the chamber 81. Air pressure will thus besupplied to the diaphragm motor, which will operate through the downward movement f its rod 77 a to force the lever downwardly to actuate the dampers 51 and 52, to open the emergency exhaust and close the passage through the return pipe. A reduction of the wet bulb temperature back to that for which the controller is adj usted will result in relieving the pressure upon the diaphragm of the diaphragm motor and the ac tuation of thedampers to their normal po' sitions.

v The invention also contemplates damper operating means controlled by the pressure or flow of water to the combined heat-recovery and air treating device 11 instead of by the thermostatic controller hereinbefore described. In Figure 13 of the drawings is illustrated one form of such a water pressure actuated controller, the same comprising a chamber 97 in which is a float 98 connected to one end of a lever 99, the lever 99 at its other end being pivotally connected to a side wall of the chamber 97. The lever 99 is pivotally connected, as shown, to the lower end of a valve member 100 mounted to slide within a casing 101 and carrying a valve 102 adapted to control the passage 103 of said casing. 99 designates a stop to limit the downward movement of the lever 99. The passage 103 is connected at one side by a pipe 104 to any suitable compressed air supply, not shown, and the passage is con nected at its other side by a pipe 104 with a diaphragm motor and damper control unit (not shown in this View) the same being similar to the diaphragm motor 77 and damper control unit as in the thermostatic control previously described and illustrated in Figure 8 of the drawings. The chamber 97 is interposed in the Water supply pipe leading to the combined heat recovery and 'air conditioning device 11. The operation of this water pressure form of control is as follows: When the proper water supply for the combined heatrecovery and air conditioning device 11 is passing through the supply pipe 25W21l381 will accumulate in the chamber 97 and the float' 98 and lever 99,

will maintain the valve 102 in a position to close the valve passage 103. Should the supply through the pipe 25 fail, the water in the chamber 7 will flow back through the inlet pipe con ected therewith, the float 98 will move downwardly, and the valve102 will be moved to a position to permit the passage of air under pressure through the passage 103 to the diaphragmmotor unit to operate the same and actuate the damper mechanism to open the emergency outlet and close the passage through the return duct section '15. Upon resumption of the water supply through "the supply pipe 25, water will again accumulate in the chamber 97,-the float 98 will rise, and the float valve lever99 and thevalve member 100 will be actuated to move .thev valve 102 to closed .position, cutting off the air supply to the diaphragm motor, which latter then operates through its spring to return the dampers to theirnormal positions.

In Figure 14 of the drawin s is illustrated one form of manually opera 1e control for .the damper means. In this view 105, designates a portion of the return duct section of the system, 105 the emergency outlet,.and

106 and 107 the dampers for controlling the emergency outlet-and closing the passage through the return duct section 104. p The dampers 106-107 and the connection therebetween is the same asin the damper operating meansherembefore described. 108109 designate the operating rods for the respec-' 'tive dampers 106107. 110 is a cable con- 'nection. between one end of the operatlng rod 108fan d one end o'fthe operating' rod 109, thecziblepassihg over a pulley 111,

operated lever-pin),

on a suitable suppqrtllti n Cpnnected y damper s4 106-107 can begactuated to openand 112is acableconnected to the other end of 'the 'operatinllgrod 109 extending over a a 50 pulley 113 and Y av ing a weight 114 secured to one end .thereoffis 115, designates a hand 'lly mounted at one end a link 117 with one ;e"n'd.; o. t :the operating rod 108 ofthe damper 106 "As'will be. understood by swingingth hand lever; the

the emergency -outlet'-105!- and close the return duct sect-ion 104-,"and vice Versa, as desired. Any suitable means is providedfor limitingthe throw of thehand lever 115 and for holding the same in its differentpositions of adjustment. In the construction shown, for this purpose, a resilient segment 118 is provided, the same being se- 132 of the hood 123.

cured to a supporting plate 119 and having notches 120121 adapted to be engaged by a projecting portion 115 on the lever 115. 'In Figures 15 and 16 of the drawings is illustrated a modified form of the apparatus, in which no heat interchanger for indirectly heating the. conditioned air by the ex-,

haust vapor is employed, the exhaustduct section being shortened and brought directly down from the exhaust apron. Additional means is also shown for introducing additional and heated air from the system into the machine room and to otherparts of the paper machine. In thcseviews illus trating this modified construction, 122 designates the series of heating rolls. 123 the machine room, and also to the paper machine at a point therein, at the wet end of the machine in advance of the series of drying'rolls. 134 is the emergency outlet and 135 136 are the dampers for controlling the emergency outlet and the passage through the return duct section 129. The automatically acting operating means or the. control for the dampers is the same as that previously described and illustrated Figures 1 to 12 of the drawings, saidcontrolling and operating. means being designated 147.

It will be noted that the invention provides for the recovery and utilization of a large proportion of the heat of the exhaustvapor, the heat recovery and conditioning of the air for re-use being effected in. the same operation. The circulation of a largevolume of conditioned aircompletely about the heating rolls and throughout the web provides fora very efiicient drying of the material. Condensation upon theweb and re: absorption thereby are prevented. Less steam pressure is required for the heating rolls, and the machine room is kept entirely free from theexhaust vapor, the improved method resulting in a considerable saving in the operation of the plant, increased production and a better quality of material.

While in the drawings are illustrated specific, embodiments of; the apparatus for practicing the improved method, it will of course be understood thatchanges and variations in the particular construction shown, and the embodiment of the apparar' tus in other forms, as will appeal to those skilled in the art and that fall within the scope of theappended claims may be practiced without departing from the spirit of the invention. Various formsfot heat interchanging devices for indirectly heating the conditioned air by the exhaust vapors may be employed. and the number of closed heaters and the location of the same in the syst-em may be varied to suit dili'ereut conditions, as may also the number of units of the combined heat recovery and air conditioning apparatus and various forms of operating means for the damper means may he used.

Subject matter disclosed but not claimed per se in this application is claimed in our copending application tiled November 8, 1922 Serial No. 598,875.

What we claim is:

1. The combination with a web drying machine of the heated roll type, of a hood arranged to extend over the machine. an exhaust apron located at one side of'the machine to receive and draw oil the vapor, and

'suction means connected with said apron.

2. The combination with a web drying machine of the heated roll type, of a hood arranged to extend over the machine, an apron located at one side of the machine, suction means connected with said apron, and means for delivering heated air adjacent the rolls.

3. The combination with a web drying machine of the heated roll type, of a hood arranged to extend over the machine, an apron located at one side of the machine, suction means connected with said apron, and means for delivering air at the other side of the machine.

4. The combination with a drying machine having material supporting and feed-- ing means, of a hood arranged to extend over the material in its passage through the machine, an exhaust apron located atone side of the machine, suction means connected with said apron and means for delivering air to the material in its passage through the machine.

5. The combination with a drying machine having supporting and material feeding means, of a hood arranged to extend .over the material in its passage through the machine, an exhaust apron located at one side oi the machine, suction means connected with said apron, and means for delivering air at the other side of the machine opposite the apron.

6. The combination with a web drying machine of the heated roll type, of an apron located at one side of the machine, suction means connected with said apron, and means for delivering air at the other side of the machine opposite the apron.

7. The combination with a web drying machine of the heated roll type, of a hood arranged to extend over the rolls, said hood having double wall portions providing a chamber therebetween and having an outlet from said chamber leading toward the rolls, means for supplying air to the said chamber in the wall of the hood, an exhaust apron for carrying 011 the vapors located at one side of the machine, and suction means connected with said apron:

8. The combination with a web drying machine of the heated roll type, of a hood arranged to extend over the rolls, said hood having double wall portions providing a chamber therebetwecn and having an outlet from said chamber leading toward the rolls, means for supplying air to the said chamber in the wall of the hood, means for delivering heated air beneath the rolls, an exhaust apron for carrying off the vapors located at one side of the machine, and suction means connected with said apron.

0. The combination with a webdrying machine of the heated roll type, of a hood arranged to extend over the rolls, said hood being provided with a chamber in the wall thereof and having a portion provided with an air outlet from the said chamber at a point at one side of the machine, an exhaust apron for carrying oil the vapor located at the opvposite side of the machine, means for supplying air to the chamber in the wall of the hood, and suction means connected with the exhaust apron.

10. The combination with a web drying machine of the heated roll type, of a hood arranged to extend over the rolls, said hood being provided with a chamber in the wall thereof and having a portion provided with an air outlet from the said chamber at a point at one side of the machine, an exhaust apron for carrying off the vapor located at the opposite side of the machine, means for supplying air to the chamber in the wall of the hood, means for delivering air beneath the rolls, and suction means connected with the exhaust apron.

11. The combination with a web drying machine of the heated roll type, of a hood arranged to extend over the rolls, said hood having an interior chamber in the wall thereof, and.having an outlet from said chamber extending along one side marginal portion thereof at one side of the machine, an exhaust apron for carrying off the vapors extending along the other side of the machine, means for supplying air to the in: terior chamber in the wall of the hood, and suction means connected with said exhaust apron. v

12. The combination with a web drying machine of the heated roll type, of a hood arranged to extend over the rolls, said hood having an interior chamber in the well thereof, and having a portion extending downwardly along one side of the machine, said said downwardly extending hood portion having an air outlet at its lower marginal part from said chamber, an exhaust apron extending along the other side of the machine, n'ieans for supplying air to the chamber in the wall of the hood, and suction means connected with said apron.

13. The combination with a web drying machine of the heated roll type, of a hood arranged to extend over the rolls, said hood having an interior chamber in the wall thereof with an outlet from saidchamber leading toward the machine, an exhaust apron extending along one side of the machine, a duct connecting the exhaust apron with the interior chamber in the wall of the hood, air

treating means interposed in said duct, and air circulating means associated with the duct. a

14. The combination with a web drying machine of the heated roll type, of a hood arranged to extend over the rolls, said hood having an interior chamber in the wall thereof, with an air inlet to said chamber at one side of the hood, and with an outlet from said chamber at the other side of the hood,

, at one side of the. machine, an exhaust apron extending along the other side of the machine, a duct connecting the exhaust apron with the inlet to the interior chamber of the hood, air. treating means interposed in said duct, and air circulating means associated with the duct.-

15. The combination with a web drying machine of the heated roll type, of a hood, arranged to extend over the rolls, said hood having an interior chamber in the wall ranged to extend over the rolls, said hood having an interior chamber in the wall thereof with an air inlet to said chamber at one side of the hood, and with an outlet from said chamber at the other side of the hood,

' at one side of the machine, an exhaust apron extending along the other side of the ma-' chine, a duct connecting the exhaust apron xrwith the inlet to the interior chamber of' "t'he'hood, means for removing moisture from the hot' air and vapors interposed in said duct, and air circulating means associated with the duct.

17.'The combination with a web drying machine of'the heated rolltype, of a 'hoo'd' arranged to extend over the rolls, said hood having an interior chamber in the wall thereof with an air inlet to said chamber at one side of the hood, and with an outlet from said chamber at the other side of the hood at one side of'the machine, an exhaust apron extending along the other side of the machine, a duct connecting the exhaust apron with the inlet to the interior chamber of the hood, means for removing moisture from the vapors, air heating means interposed in said duct, and air circulating means associated with the duct.

18. The combinatiomwith a web dryin machine, of the heated roll type, of a 1100 arranged to extend over the'rolls, said hood having an interior chamber in the wall necting the suction apron with the interior chamber in the wall of the hood, air treating means mterposed in said duct, and air circulating means associated with the duct.

19. The combination with a web drying machine of the heated roll type, of an" exhaust apron extending along one side of the machine, a hood extending over the rolls provided with an interior chamber in the wall thereof, said hood extending from a point adjacent the upper end ofthe suction apron at a downward inclination therefi om transversely of the series of rolls to the opposite ,side of the machine, and having a marginal depending part provided with an air outlet extending longitudinally thereof to deliver air to the rolls at that side of the machine, means for supplying air to the interior chamber in the wall of the hood at the side thereof opposite the air outlet from said chamber, and suction means connected with the exhaust apron.

20. The combination with a web drying machine of the heated roll' type, of an exhaust apron extending along one side of the machine, a hood extending over the machine provided with an interior chamber in the wall thereof, said hood extending from a point adjacent the upper end of the apron transversely of the series of rolls to the opposite side of the machine and having a marginal depending part prov ded with an air outlet extending longitudinally thereof to deliver air to the rolls at that side of the machine, means-for supplying air to the ;m-

terior chamber in the wall of the hood, and

suction means connected with. the exhaust apron. 0

21. The comblnatlon with a web drying machine of theheated roll type, of an exhaust apron ext-ending along one side of the machine, a hood arranged to extend over the rolls, said hoodhaving an interior chamber in the wall thereof, and having a portion exdrying machine,

tending downwardly along one side of the machine, said downwardly extending portion terminating short of the bottom of the series of rolls leaving an opening at this point for inducing a flow of air from the machine room, and said downwardly extending hood portion having an air outlet at its lower marginal part from said chamber, an exhaust apron extending along the other side of the machine, means for supplying air to the chamber in the wall of the hood, and suction means connected with said apron.

22. The combination with a drying machine from which hot air and vapor are given off, of means for Withdrawing the hot air and vapor from the drying machine, a duct leading from said means back to the drying machine, air circulating means interposed in said duct, and air conditioning and water heating means interposed in the duct, said last mentioned means includingimeans for circulating water in a finely divi ed condition within the chamber in the path of the hot air and vapor to heat the water and dry the air, and means for withdrawing the heated water from the chamber.

23. The combination with a drying machine from which hot air and vapor are given off, of means for withdrawing the hot air and vapor from the drying machine, a duct leading from said means back to the air circulating means interposed in said duct, and air conditioning and water heating means interposed in the duct, said last mentioned meansincluding a chamber and means for discharging water in fine sprays into said chamber in the path of the exhaust vapor in successive stages at different points along the same, said means comprising a plurality of spray devices located at intervals along 'the chamber, a series of troughs within the chamber to receive the water from the res ective spray devices, and circulating means or the water.

24. The combination with a drying machine from which hot air and vapor are given off, of means for withdrawing the hot air and vapor from the drying machine, a duct leading from said means back to the drying machine, air circulating means interposed in said duct, and air conditioning and water heating means interposed in the duct, said last mentioned means including a chamber, means within the chamber for agitating the vapor in its passage therethrough, and means for discharging water in a fine spray into the chamber in the path of the vapor, and means for drawing ofi the heated water from the chamber.

25.- The combination with a drying machine from which hot air and vapor are given off, of means for withdrawing the hot air and vapor from the drying machine, a duct leading from said means to the drying machine, air circulating means interposed in given off, of means for withdrawing the hot air and vapor from the drying machine, a

duct leading from said means back to they drying machine, air circulating means interposed in said duct, and air conditioning and water heating means interposed in the duct, said last mentioned means including a chamber, means for circulating water in a finely divided condition in successive stages to the influence of the vapor passing through said chamber, said means comprising a device for discharging water in a fine spray into the chamber in the path of the vapor, a closed heater in the chamber in the path of the vapors, and circulating means for the water.

27'. The combination with a drying machine from which hot air and vapor are given off, of means for withdrawing the hot air and vapor from the drying machine, a duct leadingfrom said means back to the drying machine, air circulating means interposed in said duct, air conditioning and wa- :ter' heating means interposed in the duct,

said last mentioned means including a chamber, means for circulating water in a finely divided condition in successive stages to the influence of the vapor passing through said chamber, said means comprising means for discharging water. in a fine spray into the chamber in the path of the vapor, and a closed heater in the chamber in the path of the vapors.

28. The combination with a drying machine from which hot air and vapor are given off, of means for withdrawing the hot air and vapor from the drying machine, a duct leading from said means to the drying machine, air circulating means interposed in said duct, and air conditioning and water heating means interposed in the duct, said last mentioned means including a chamber, means for discharging water in fine sprays into the chamber in the path of the vaporin successive stages at different points alon the same, and series of bafile plates locate at intervals along said chamber, one of said series of bafile plates being located in ad Vance of each one of the water sprays.

29. The combination with a drying machine from which hot air and vapor are given off, of means for collecting the exhaust hot air and vapor from the drying machine, a duct leading from said collecting means back to the drying machine, air 

